SSCP2313
Tutorial 5
1.
Briefly, explain the followings: Conductor, insulator, semiconductor, silicon crystal, valence
band, conduction band, current carriers, free electrons, holes, intrinsic semiconductor,
extrinsic semiconductor, majority carrier, minority carrier, doping, acceptor, donor, n-type
semiconductor, p-type semiconductor, recombination, lifetime.
2.
Briefly, explain the followings: pn junction, depletion layer, barrier potential, junction
voltage, forward bias, reverse bias, leakage current, breakdown voltage, bulk resistance,
avalanche, Zener effect, rectifier diode.
3.
Sketch the diode I-V (current-voltage) characteristic for
a) a practical diode
b) an ideal diode approximation
c) a semi-ideal diode approximation (ideal diode with junction voltage)
4.
Diode D1 and D2 in Figure 1(a) have an I-V characteristic shown in Figure 1(b). Find the
voltage across AC and BC.
I (A)
D1
A
D2
B
0.4
20
10V
30
0.2
V (volt)
1
C
Fig. 1(b)
Fig. 1(a)
5.
2
In the circuits in Figure 2(a), (b), (c), (d), (e) and (f), vi is a sinusoidal voltage with peak
value of 5V. By using the semi-ideal diode approach with junction voltage of 0.7V, sketch
the output voltage, vo for each circuit.
Vz=2.7V
vi
vo
vo
vi
(a)
vo
vi
(e)
(c)
Vz=2.7V
vo
vi
vi
(b)
vo
(d)
Fig. 2
vi
vo
(f)
vi
6.
In the circuits in Figure 4(a), (b), (c), (d), (e), and
(f), the input voltage, vi is shown in Figure 3. By
assuming all diodes are ideal (zener diode ideal for
forward biased) sketch the output voltage, vo for
each circuit.
30V
t
-30V
Fig. 3
Fig. 4
2k
(a) vi
10k
4k
(b) vi
vo
vo
12V
Vz=5.7V
(c) vi
Vz=10V
vo
(d) vi
Vz=5.1V
Vz=5.7V
vo
Vz=10V
(f)
4k
(e) vi
6k
7.
vi
vo
vo
For the circuits in Figure 5(a) and (b), sketch the output voltage vo. What is the reading of (i)
DC voltmeter and (ii) AC voltmeter when connected to the output terminals?
vo
8:1
8:1
240V
AC
vo
240V
AC
(a)
(b)
Fig. 5